Glass reheating and reshaping



Oct- 1 1952 G. E. STONG GLASS REHEATING AND RESHAPING E., h .ml v, Nimm ,mmrlg f, .r 5m r. mt 0 G o H Mw,.r wm N llm. E

Filed April 2l, 1947 Patented Oct. 14, 1952 GLASS REHEATING AND `RESHAPING:

Guy E. Stong, Elmira, N. Y., assignor to Corning Glass Works, Corning, N. Y., a corporation of 'New York Application AprilZl, 1947, Serial No. 742,918

6 Claims.

The present `inventionrelates tothe production of linear rglass bodies of desired precise shape characteristics andparticularly to the production of tubing'having an extremely accurate bore.

The prime object of the invention is the production of 4a linear body of glass having precise .cross-sectional dimensional characteristics.

`Another object is the economic -production of tubular articles of precise' internal dimension.

`A further object is a method adaptable tothe production of tubular articles `of either circular or non-circular bore configuration.

These objects are realized in a `'system which utilizes as the starting material linear glass bodies 'inexpensively .made .on .high production machines and involves slowly `advancing a body ofsuchfmaterial into a furnace-and drawing the softened glass through a die or over the .end of a mandrel of a desired cross-sectional configuration until the body of starting materialhas been consumed.

. ,In order to assist .in a clear understanding vof the invention, reference is made to. `the accompanying drawing, Fig. 1 of -Whichvillustratesan .apparatus `embodying theinvention in the process of redrawing tubing to .impart to it a desired' Thetube feeding equipment compri-ses a tube chuck I3 `attached to a carriage I5 having halfnuts I6 and l1 (Fig. 2) threaded on a screw I8. The carriage I is moved from left to right by rotation of screw I8 through the medium of a chain drive I9, a speed changer 26, and the drive motor I2. Return of the carriage I5 to the left end of-screw I8 is accomplished by separation of lthe half-nuts I6 and II and returning the carriage by operation of a crank 22 connected to a shaft 23 carrying a pinion l2li in mesh with a frack 325. The half-,nuts I6 `and I1 areopened `and closed labout screw I8 by means of pins 26 and 21 projecting therefrom and occupying cam slots 28 and 29 in a plate 30 carried on the end of a shaft 3l passing through the carriage I5 land 2 provided with an operating lever 32 (Figs. '2 and 3).

The tube chuck I3 comprises an enclosed `spool of rubber 36 having a surrounding air chamber 31 into which air may be introduced from a line 38 through a valve 39 to force the spool 36 vinto intimate contact with a glass tube 40. Chuck `I3 has an additional chamber 4I to which a Vacuum line `42 is connected-via a valve 43 to create subatmospheric pressures within the'bore Vof tube 40. Passing through chuck I3 is a mandrel support 45 .whose free end carries a former or mandrel 46 and whose opposite end is held by a chuck 41. Chuck A1 is attached to one end of a push rod 49 adapted to be reciprocatedjointly by means of ra cam .50 rotatable by a motor 5I and by a return spring 52. To initiallyhold the mandrel 46 at the free ,end of support 45 centrally disposed within the bore of tube III), aspacer washer may be arranged on the support. M-otor 5I is preferably mounted on a. carriage 53 adapted for manual movement by means of a crank 54 to enable vchanging of the position o'f mandrel 46 to meet varying `operating conditions, as will bebrought outlater.

The tube drawing equipment may be of the caterpillar tractor or roller type. For the sake of simplicity, a single driven roller isvshown as being heldin frictional engagement with lthe tubing 4D, after passing over mandrel 4,6, by means of Va roller 6I which of .course may also be Idriven if desired. Roller 60 is driven by motor I2 through the medium of a speed reducer 65 and chain drives 66 and 61. vAs will be understood, the relative speed-s o-f feeding and drawing .can be Ichanged by changing the setting of speed changer 20. On the other hand, the speed `of operation may be changed While the relative feed and draw speeds are retained intact by operation of a motor rheostat R.

To suitably heat mandrel 46 and to progressively heat the tube 40 as it is fed to the mandrel, there is preferably provided a suitable electric furnace 10 through which the tubing is passed. Suitable rollers lll-.13 for aiding in supporting the tubing may be also provided.

.Operation T-o start a tube resizing operation, 4a tube III) is threaded over mandrel 46 and projected `into chuck I3. Valve 39 is then actuated tofsupply air to chamber 31 to effect seizure of the surrounded end of tube 40. The carriage I5 maybe yset to initially bring the opposite end of tube 40 to a point intermediate the end of furnace 10 and it passes beyond rollers til and S I.

drawing roller Si) or, alternatively, the carriage may be set to bring the end of the tube between rollers 60 and 6| as illustrated in Fig. 4. Crank 54 is also actuated to draw the mandrel 46 back to the position illustrated in Fig. 4 so as to bring its free end well into the furnace so that it can be rapidly heated to its normal operating temperature.

When the tube 4G reaches softening temperature, as indicated by its sagging condition illustrated in Fig. 4, motor 5i is started, to reciprocate mandrel 46 to reduce the danger of the molten glass sticking to it, and the free end of tube 4i) is seized, drawn forward and placed between rollers Gl and 6i, if it has not initially been placed between the rollers. The motor I2 is then started to initiate the feed and draw. As will be understood, the rate at which the tube 40 can be fed into furnace l0 depends on its diameter and wall thickness and the heat capacity of furnace lli. The rate of draw is determined by the rate at which tube 4D is softened, and by the amount of glass per unit of length of precision bore tubing to be produced. The proper feed and draw rates are of course attained by appropriate adjustment ofrheostat R and speed changer 20 during the early stages of a draw. As soon as drawing begins, the softened portion of the tube 4) is drawn into contact with the mandrel 46 after which valve 43 may be opened to create a subatmospheric pressure in the bore 4S to thus assist the drawing operation in holding the softened glass in intimate contact with the mandrel. rl'his is particularly important if the cross-sectional configuration of the mandrel or former isother than circular to insure accurate reproduction of the mandrel configuration on the bore wall. The next step in the operation is the actuation of crank 54 to advance the mandrel until its free end projects far enough out of the furnace l0 that tubing drawn olf the end thereof is sufficiently rigid to maintain desired bore and wall dimensions for a given rate of draw as determined conveniently by applying a tolerance gage to the tube as it issues from the mandrel.

As will be understood, a single tube fifi, of say six feet in length, may contain enough glass to produce sixty or seventy or even more feet of precision bore tubing,` and this can easily be cracked off in convenient lengths for handling as Furthermore, the reciprocation of the mandrel t-o prevent its sticking to the glass places no limitation on its cross-sectional configuration and accordingly fiat or other non-circular precision bore tubing can be produced as easily as can circular bore tubing. Preferably, the mandrel is coated from time to time with a lubricant, such as colloidal `graphite or the like.

What is claimed is:

1. ln an apparatus for progressively reheating and reshaping a linear body of glass, a former, means for progressively heating the body to a workable temperature, means for passingly engaging the glass'solely with said former while the glass is at a workable temperature, and means for imparting a linear reciprocating movement to said former relative to the glass along a path paralleling that of the glass as it is being passingly engaged by the body.

2. Apparatus for forming a substantial length of precision bore relatively thin-walled glass tubing from a relatively short length blank of glass tubing, comprising a holder for the rear end of the blank, a tractor for the support of the front end of the blank and for the thinwalled tubing to be drawn, a former, a support for said former passing through said holder, means for reciprocatingA said support in a plane parallel to the direction of draw, means for heating a localized area of the blank near the end thereof supported by said tractor, and means for actuating said tractor as required to draw thinwalled tubing off the end of said former.

3. In a glass tube reheating and reshaping apparatus, a chuck for receipt of one end of a tube to be reheated and reshaped, a furnace, means for moving said chuck to slowly advance the tube into said furnace to progressively locally heat it along its length, a tractor for gripping the other end of the tube, means for actuating said tractor to draw the'tube therethrough at a relatively rapid rate to elongate the tube as it is being drawn, a mandrel occupying the bore of the tube in the area in which it is locally heated, a support for said mandrel, and a reciprocating device to which said ysupport is anchored.

4. The method of making relatively thin-walled tubing of accurate bore from relatively heavy walled tubing, which comprises advancing the heavy walled tubing into a heated atmosphere at a relatively slow rate of speed, drawing the softened portion of the tube into intimate contact with a former, and drawing the glass off the end thereof at a relatively rapid rate while imparting reciprocating movement to the former.

5. In a glasstube reheating and reshaping apparatus, a chuck for receipt of one end of a tube to be reheated and reshaped, a furnace, means for moving said chuck to advance the tube slow- 1y into said furnace to progressively locally heat the tube along its length, a mandrel within the bore of the tube in the area in which it is locally heated, means for reciprocating said mandrel, means for gripping the other end of the tube, and means for actuating said gripping means to move said other end of the tube away from said furnace at a relatively rapid rate to draw said tube onto said mandrel and to elongate the tube as it is being drawn.

6. The method of making relatively thin Walled tubing of accurate bore from relatively heavy walled tubing, which comprises drawing the heavy walled tubing into intimate contact with a former while heating said tubing only in the vicinity of the former, and drawing relatively thin walled tubing off the end of said former at a `relatively rapid rate while imparting reciprocating movement to said former.

lGUY E. sToNG.

REFERENCES CITED The following references are of record in the iile of this patent:

UNITED STATES PATENTS Great Britain Sept. 16, 1942 

